/*
 * This software and all files contained in it are distrubted under the MIT license.
 * 
 * Copyright (c) 2013 Cogito Learning Ltd
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package net.mitza.rel.parser.expression;

import net.mitza.rel.parser.TokenTypes;

/**
 * An ExpressionNode that handles exponentiation. The node holds a base and an exponent and calulates base^exponent
 * 
 */
public class ExponentiationExpressionNode extends ExpressionNode {

	/** the node containing the base */
	private ExpressionNode base;
	/** the node containing the exponent */
	private ExpressionNode exponent;

	/**
	 * Construct the ExponentiationExpressionNode with base and exponent
	 * 
	 * @param base
	 *            the node containing the base
	 * @param exponent
	 *            the node containing the exponent
	 */
	public ExponentiationExpressionNode(ExpressionNode base, ExpressionNode exponent) {
		this.base = base;
		this.exponent = exponent;
	}

	/**
	 * Returns the type of the node, in this case ExpressionNode.EXPONENTIATION
	 */
	public TokenTypes getType() {
		return TokenTypes.EXPONENTIATION;
	}

	/**
	 * Returns the value of the sub-expression that is rooted at this node.
	 * 
	 * Calculates base^exponent
	 */
	public Object getValue() {
		Object baseValue = applyType(base.getValue());
		Object exponentValue = applyType(exponent.getValue());
		if (baseValue instanceof Double && exponentValue instanceof Double) {
			return Math.pow((Double) baseValue, (Double) exponentValue);
		} else {
			throw new EvaluationException("Exponentiation accepted between two numbers, but found instead " +
					baseValue + " and " + exponentValue);
		}
	}

	/**
	 * Implementation of the visitor design pattern.
	 * 
	 * Calls visit on the visitor and then passes the visitor on to the accept method of the base and the exponent.
	 * 
	 * @param visitor
	 *            the visitor
	 */
	public void accept(ExpressionNodeVisitor visitor) {
		visitor.visit(this);
		base.accept(visitor);
		exponent.accept(visitor);
	}

	@Override
	public String toString() {
		return String.format("%s ^ %s", base.getValue(), exponent.getValue());
	}
}
